1. Field of the Invention
The present invention relates to an embroidery data producing apparatus for an embroidery machine which is capable of forming an embroidery stitch based on embroidery data.
2. Description of Related Art
An embroidery data producing apparatus is disclosed in U.S. Pat. No. 4,849,902. According to the embroidery data producing apparatus, when an operator sets an embroidery area where embroidery stitches are to be formed and division lines are defined for dividing the embroidery area, the embroidery area is automatically divided into a plurality of blocks, and block data is converted into embroidery data. The block data has information about the vertexes of each block of the divided embroidery area. When the block data is supplied to an embroidery machine, the embroidery machine automatically creates stitch data based on the block data so as to form the embroidery stitches on the embroidery area. Therefore, the embroidery area is covered with a plurality of the embroidery stitches, so that an embroidery pattern is formed. The stitch data has information about sewing positions where the embroidery stitches are to be formed.
If an embroidery machine does not have a function for automatically creating the stitch data based on the block data, the stitch data is produced as the embroidery data based on the block data by an embroidery data producing apparatus, and the stitch data is supplied to the embroidery machine. Therefore, the embroidery data is equivalent to the block data or the stitch data.
U.S. Pat. No. 5,054,408 discloses an embroidery data producing apparatus which can compute block data from embroidery data. The embroidery data producing apparatus automatically sets a plurality of division lines for dividing an embroidery area on which a plurality of embroidery stitches are to be formed, based on an embroidery direction, and automatically divides the embroidery area. Therefore, according to the embroidery data producing apparatus, the operator need not set the division lines.
A conventional embroidery data producing apparatus can create embroidery data even if the embroidery area of one embroidery pattern is composed of a plurality of embroidery areas. However, it often happens that a plurality of embroidery areas mutually overlap. If the embroidery stitches are formed in accordance to the embroidery data created in such case, the overlap area where a plurality of embroidery areas mutually overlap is covered with the embroidery stitches a plurality of times or overstitched. For instance, an embroidery area 100 of a pattern shown in FIG. 9A comprises three embroidery areas 101, 102 and 103. The embroidery area 101 and the embroidery area 102 have an overlap area at an almost center position of each. FIG. 9B shows a plurality of embroidery stitches which are formed in accordance to the embroidery data which is created by the embroidery data producing apparatus. As shown in FIG. 9B, the overlap area where the embroidery area 101 and the embroidery area 102 overlap each other is covered twice with the embroidery stitches.
As described above, in the case that the embroidery stitches are formed in accordance to the embroidery data made by the conventional embroidery data producing apparatus, it is possible that an area is generated which is covered with embroidery stitches a plurality of times. The area which is covered with the embroidery stitches a plurality of times becomes thicker than the other area. Therefore, the appearance of the formed embroidery pattern becomes unsightly. The operator has to modify the embroidery data made by the embroidery data producing apparatus in order to prevent generation of the area covered with the embroidery stitches a plurality of times. In the case that the embroidery area is wide or there are many areas to be covered with embroidery stitches a plurality of times, it is very troublesome for the operator to modify the embroidery data. Moreover, it is possible that the operator may make a mistake while modifying the embroidery data.